import crypto from 'node:crypto';

function newId() {
  return crypto.randomUUID();
}

function nowMs() {
  return Date.now();
}

function hashJson(obj) {
  return crypto.createHash('sha256').update(JSON.stringify(obj)).digest('hex');
}

/**
 * @param {import('mysql2/promise').Pool} pool
 * @param {string} userId
 * @param {object} options
 */
export async function materializeProfileAndSnapshot(pool, userId, options = {}) {
  const projection = options.projection ?? 'default';
  const reason = options.reason ?? 'candidate_accepted';
  const ts = nowMs();

  const [projects] = await pool.query(
    `SELECT e.canonical_name, a.confidence, a.effective_weight, a.last_seen_at
     FROM um_entities e
     JOIN um_attributes a ON a.entity_id = e.entity_id AND a.status = 'active'
     WHERE e.user_id = ? AND e.entity_type = 'project' AND e.status = 'active'
     ORDER BY a.effective_weight DESC
     LIMIT 8`,
    [userId],
  );

  const [focusCandidates] = await pool.query(
    `SELECT hypothesis_json, confidence, promotion_score, last_seen_at
     FROM um_candidates
     WHERE user_id = ? AND candidate_type = 'focus' AND status IN ('open', 'accepted')
     ORDER BY promotion_score DESC
     LIMIT 10`,
    [userId],
  );

  const [versionRows] = await pool.query(
    `SELECT COALESCE(MAX(profile_version), 0) AS v FROM um_profile_versions WHERE user_id = ?`,
    [userId],
  );
  const profileVersion = Number(versionRows[0]?.v ?? 0) + 1;

  const activeProjects = projects.map((row) => ({
    id: `project_${String(row.canonical_name).toLowerCase().replace(/[^a-z0-9]+/g, '_')}`,
    name: row.canonical_name,
    status: 'active',
    confidence: Number(row.confidence),
    last_seen: row.last_seen_at,
  }));

  const recentFocus = focusCandidates.map((row) => {
    const h = typeof row.hypothesis_json === 'string' ? JSON.parse(row.hypothesis_json) : row.hypothesis_json;
    return {
      topic: h.topic ?? h.name ?? 'unknown',
      weight: Number(row.promotion_score),
      ttl_days: 14,
    };
  });

  const structured = {
    identity: [],
    active_projects: activeProjects,
    recent_focus: recentFocus,
    technical_preferences: [],
    working_style: [],
  };

  const structuredHash = hashJson(structured);
  await pool.query(
    `UPDATE um_profile_versions SET status = 'superseded' WHERE user_id = ? AND status = 'active'`,
    [userId],
  );
  await pool.query(
    `INSERT INTO um_profile_versions
     (profile_version, user_id, structured_json, content_hash, parent_version, materialize_reason, created_at, status)
     VALUES (?, ?, ?, ?, ?, ?, ?, 'active')`,
    [
      profileVersion,
      userId,
      JSON.stringify(structured),
      structuredHash,
      profileVersion > 1 ? profileVersion - 1 : null,
      reason,
      ts,
    ],
  );

  const [fastRows] = await pool.query(
    `SELECT COALESCE(MAX(fast_revision), 0) AS r FROM um_profile_snapshots WHERE user_id = ? AND projection = ?`,
    [userId, projection],
  );
  const fastRevision = Number(fastRows[0]?.r ?? 0) + 1;

  const agentHints = [];
  if (activeProjects[0]) agentHints.push(`近期重点：${activeProjects[0].name}`);
  if (recentFocus[0]) agentHints.push(`关注话题：${recentFocus[0].topic}`);

  const snapshotCore = {
    identity: structured.identity,
    active_projects: activeProjects,
    recent_focus: recentFocus,
    technical_preferences: structured.technical_preferences,
    working_style: structured.working_style,
    agent_hints: agentHints,
  };

  const snapshotBody = {
    profile_version: profileVersion,
    fast_revision: fastRevision,
    projection,
    core: snapshotCore,
    meta: {
      graph_entity_count: activeProjects.length,
      open_candidates: recentFocus.length,
    },
  };

  const snapshotJson = {
    ...snapshotBody,
    stale_after_sec: 3600,
  };
  const snapshotStr = JSON.stringify(snapshotCore);
  const byteSize = Buffer.byteLength(snapshotStr, 'utf8');
  const contentHash = hashJson(snapshotBody);

  await pool.query(
    `UPDATE um_profile_snapshots SET status = 'superseded' WHERE user_id = ? AND projection = ? AND status = 'active'`,
    [userId, projection],
  );

  const snapshotId = newId();
  await pool.query(
    `INSERT INTO um_profile_snapshots
     (snapshot_id, user_id, projection, profile_version, fast_revision, snapshot_json, byte_size,
      content_hash, created_at, status)
     VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, 'active')`,
    [
      snapshotId,
      userId,
      projection,
      profileVersion,
      fastRevision,
      JSON.stringify(snapshotJson),
      byteSize,
      contentHash,
      ts,
    ],
  );

  return {
    profile_version: profileVersion,
    fast_revision: fastRevision,
    snapshot_id: snapshotId,
    content_hash: contentHash,
    byte_size: byteSize,
  };
}

export async function getActiveSnapshot(pool, userId, projection = 'default') {
  const [rows] = await pool.query(
    `SELECT snapshot_id, user_id, projection, profile_version, fast_revision, snapshot_json,
            byte_size, content_hash, created_at
     FROM um_profile_snapshots
     WHERE user_id = ? AND projection = ? AND status = 'active'
     ORDER BY created_at DESC
     LIMIT 1`,
    [userId, projection],
  );
  const row = rows[0];
  if (!row) return null;
  const snapshotJson =
    typeof row.snapshot_json === 'string' ? JSON.parse(row.snapshot_json) : row.snapshot_json;
  return {
    snapshot_id: row.snapshot_id,
    user_id: row.user_id,
    projection: row.projection,
    profile_version: row.profile_version,
    fast_revision: row.fast_revision,
    content_hash: row.content_hash,
    byte_size: row.byte_size,
    stale_after_sec: snapshotJson.stale_after_sec ?? 3600,
    core: snapshotJson.core ?? snapshotJson,
    meta: snapshotJson.meta ?? {},
    created_at: row.created_at,
  };
}

export async function getSnapshotInfo(pool, userId, projection = 'default') {
  const snap = await getActiveSnapshot(pool, userId, projection);
  if (!snap) return null;
  return {
    profile_version: snap.profile_version,
    fast_revision: snap.fast_revision,
    content_hash: snap.content_hash,
    projection: snap.projection,
    snapshot_id: snap.snapshot_id,
  };
}